JPH0716815B2 - Method for precision machining crowned tooth flanks of hardened gears - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field and Prior Art] The present invention is derived from the state of the art known from West German Patent No. 3123502. The machine described therein is, firstly, for the precision machining of the tooth flanks of a gear that has not (yet) been hardened, that is to say by means of a shaving cutter, which is also parasol, diagonal or underpass. Is intended to shave gears. However, the machine is also used for precision machining of the tooth flanks of hardened gears with abrasive tools, ie honing, refining, shaving grinding, etc. (there is no unified definition of these methods). It can also be used, albeit in a limited manner, to However, especially in the case of the diagonal method and the underpass method, the tool wears down fairly quickly, and as a result, these methods have not been so popular until now, although the processing time is shorter than that of the parallel method. .

When trying to crown a tooth surface of an unmachined gear, in the parallel method and the diagonal method, a uniform tooth surface of the crowning will be formed only along the entire width of the gear. This is because the tool makes a swiveling motion in dependence on a longitudinal feed or a diagonal feed (the radial feed is further added to the same feed).

The method of precision machining of hardened gears is also known ("Werkstatt und Betrieb (factory and operation)", Vol. 118 (1985), No. 8, pp. 505-509, here 506). In the same way, the polishing tool is moved parallel to the axis of the workpiece and, in addition, the radial infeed is intermittent. In this case, the swivel motion of the workpiece is superimposed on the longitudinal feed in order to crown the tooth surface. However, this vertical feed is
In the case of the method mentioned at the beginning as well-a long processing time is required and should therefore be avoided if possible.

In another known method, the tool is fluttered radially, which allows a relatively short machining time. In order to machine a workpiece tooth over its entire width, the tool tooth must match the workpiece tooth, which presents certain problems in the manufacture of the tool. This problem occurs remarkably when trying to crown the tooth surface. This is because the workpiece must additionally be crowned in a complementary manner. Only in the end regions of the tooth flanks, i.e. in the regions adjacent to the tooth flanks, can the tooth flanks be crowned only by an underpass method with a specially difficult tool.

[Problems to be solved by the invention]

The problem underlying the present invention is based on the above-mentioned drawbacks pointed out for this known method, in which the tooth flanks of the hardened gears are subjected to a minimum possible wear of the tool in a reasonable time. , So that you can add crowning,
It is to improve the method described at the beginning.

[Means for solving problems]

This problem is solved by a method having the features of claim 1. The teeth of the workpiece are first machined as a whole with normal precision, and only at the end, at the end of the tooth,
It has been found that cutting away excess material for crowning is effective in setting or programming the machine.

Substantial improvements are achieved by the method according to the improvements of claim 2. This method is supplemented by the features of claim 3. That is, it has been found that the above-mentioned significant tool wear is due to the relatively high hardness of the tooth ends of the workpiece. Therefore, the removal of the machining allowance is performed "inside" to some extent. That is, processing is the first
In addition, without taking into account crowning, it is carried out in a less hard region of the tooth surface, and only at the end of precision machining, the material of the very hard tooth end is cut out and at the same time the desired crowning is applied. . West German Patent Invention No. 3123
The machine described in 502 is not suitable for carrying out the method of the invention. A suitable machine is described further below.

The initially machined area, which is not so hard, remains unchanged while the infeed feed (plunge feed) is still taking place, but can also be gradually expanded (claims 4 and 5). However, the axial intersection will never move beyond the edge of the tooth flank.

In a helical tooth, there is a possibility that secondary burr will occur at the tooth end with an acute angle, so horizontal feed is appropriately started from a position other than the center (Claim 6), which is also close to the obtuse tooth end. Start at the point you made. That point is also the turning point for horizontal feed. At this point, the rotation speed of the tool / workpiece pair will be increased to start precision machining.

The method of the invention is further improved by the features of claim 7 or 8, which contributes significantly to the quality improvement of the surface formed on the tooth flank of the workpiece.

In this way, the tool is always moved relative to the work piece along one direction that extends obliquely to the axis of the work piece. In this case, when the teeth of the tool are correspondingly modified in order to machine the teeth of the workpiece over its entire width, i.e. when the teeth of the tool are concave, when shaving a gear by the diagonal method. Processing will be performed with a short feed amount, such as. However, due to the measure of the invention that the tool can be tilted at the end of the precision machining in order to crown the tooth surface, the unmodified tooth surface is not finished to be concave. It is also possible to use tools with tooth flanks.

Particularly in the method according to claim 1 or the horizontal feed without plunge feed according to claim 2 or 4, depending on the width of the tool and the angle selected for horizontal feed with respect to the axis of the workpiece, the contact point. Alternatively, a relatively short feed is sufficient to transfer the common perpendicular from one end of the workpiece tooth through the tooth width to the other end. It is therefore advantageous to improve the method according to claim 10 in order to obtain the most possible feed.

〔Example〕

FIGS. 1 and 2 show a so-called hard shaving machine or a grinding machine for precisely machining a hardened gear (workpiece). A workpiece W is housed on a machine bed 11 between tailstocks 12 and 13 in a rotatable manner. A motor (not shown) required for this rotational drive is housed in a column 15, and a feed carriage 16 is vertically slidable in the column (arrow direction Z), and for that purpose, It can be driven by a motor 17 via a transmission belt 14 and a spider 18. The feed carriage 20 is housed in a circular guide (not shown) in the feed carriage 16 so as to be rotationally adjustable about a vertical line 21. The feed carriage 20 is capable of reciprocating sliding in the horizontal direction relative to the feed carriage 16 (arrow direction X), and therefore, the motor
22 and a spindle 23 are provided.

A locker 25 is arranged in an arc guide 24 on the lower surface of the feed carriage 20. In this locker, a tool head 27 is rotationally adjustable about a vertical axis 28 in a circular guide (not shown). It is housed. A hard shaving cutter (tool T) is rotatably supported in the tool head 27. This hard shaving cutter will be described in more detail. The axes 21, 28 are aligned with each other and lie in the central plane of rotation 29 of the tool T.

When the tool head 27 is rotated with the locker 25 about an axis 28 (for this purpose a motor 30 with a rod 31 is provided), the axis between the axis 3 of the tool T and the axis 4 of the workpiece W is The crossing angle γ is adjusted. At this time, the axes 3 and 4 exist in planes parallel to each other. Feed carriage 20 axis
When it is rotated around 21 (for this purpose a motor 34 with a transmission 35 is provided), the tilt angle ε of the feed direction X of the tool T with respect to the axis 4 of the workpiece is adjusted. It In FIG. 1 and FIG. 2, in order to improve the visibility as much as possible, the tool T and the workpiece W have the axial intersection angle γ =
It is shown at 0 ° and at a diagonal angle ε = 0 °. That is, the axes will be machined in a parallel fashion (not really possible) without crossing. A tool head 27 and a locker 25 with a tool T are swingable in an arc guide 24 about an axis 10 which at least approximately abuts the pitch cylinder of the tool T on the underside of the tool T. There is. A motor 32 with a worm gearbox 33 is provided for this oscillating movement.

In order to precisely machine the tooth flank of the workpiece W, the tool T and the workpiece W are intermeshed with each other, also intersecting the axes 3,4 (FIGS. 3,4). The tool T comprises at least at its tooth flank 5 a polished surface, i.e. a surface which does not have a unidirectional cutting edge. The tool usually consists of a metal base with teeth, the tooth flanks 5 of which are
For example, it is provided with a hard abrasive grain layer of cubic boron nitride (CBN) or diamond. (When processing a gear that has not yet been quenched, it is possible to make the entire tool T from a ceramic or synthetic resin in which abrasive grains are embedded.) The teeth of the tool T are oriented along the teeth. Has not been modified in. Teeth of this kind should be manufactured with the required accuracy, slightly less than the modified teeth, especially if the tool is coated. This is because the CBN or diamond coated teeth can be modified only after a great deal of work, time and cost.

In order to carry out the machining, the tool T or-on the machine described above-is rotated, and the workpiece W is in each case rotated by the other member.
It is rotated through the teeth. During this rotation, the tool T
The workpiece W is reciprocated along the arrow direction X relative to the workpiece W. This horizontal feed is performed in a plane parallel to the axes 3 and 4. In addition to the horizontal feed X, a radial feed along the arrow direction Z is performed intermittently or continuously thereto. The direction of rotation can be reversed once or several times. This interlocking will be described in more detail.

Theoretically, there is a point contact at a contact N between the tool T and the workpiece W, and this contact point is a so-called common perpendicular (axis).
It is a virtual line that connects between 3 and 4, and is on a line perpendicular to both axes. During horizontal feed X, this contact point is the end face 8, 9 of the workpiece W.
Change position between. That is, this contact point passes from one unit value M on one end face 8 to the intermediate position (the position where the contact point N exists) on the other end face 9 on the other end face 0.
Move up to. Specific relationships must be maintained to achieve this at the shortest possible feed rate.

Between the diagonal angle ε, that is, the angle formed by the axis 4 and the horizontal feed direction X, and the axis intersection angle γ formed by the axes 3 and 4, the following relational expression It turned out that should be established. These dimensions are shown in FIG. 5 for ease of understanding.
In the figure, the feed amount, which is to be advanced in order to bring the contact point N from the illustrated center position to the end position 0, is represented by S, and in that case still overlaps in the projection of the workpiece W. The right part of the width of the tool T is represented by u. b _T and b _W represent the widths of the tool T and the workpiece W.

When advancing the process shown in FIG. 6, the tool T is first engaged with the workpiece W, to be precise, in the machining where there is two flank contact between the tool T and the workpiece W. Until fast starting point 40 is reached, meshing is carried out by reducing the axial spacing, initially fast and then extremely slow and feeding vertically along the radial direction. The work piece has already been displaced somewhat earlier in the direction of rotation when there was still a gap between the teeth of the tool T and the work piece W. The tooth causes the workpiece W to be displaced in the direction of rotation.
Then, when horizontal feed is performed to the point 41, the contact point N moves from the center position to the end position 0 on the end face 9. Where the point
43 (at this point the contact point is the opposite end face 8 of the workpiece
To reach the other end position M in. ) Is fed to point 42 before the reverse horizontal feed to). At point 43, a new feed is made to point 44 and then to level 45 again. These steps are repeated several times. The final horizontal feed from point 46 to point 47 and back to point 48 (contact point N is again in the centered position) occurs without intervening forward or intermediate feeds. Before the tool T and the workpiece W are separated from each other again, the tool T is pulled back slightly from the point 48 to the point 49, and a new reciprocating motion (points 49, 50, 5
1,52) can be interposed. Such a reciprocating motion is used to grind the tooth flank without further cutting a considerable amount of material.

In the case of the process shown in FIG. 7, horizontal and infeed feeds are carried out synchronously, starting from the starting point 60. That is, the infeed feed and the horizontal feed overlap. After making several round trips, reach point 61. Here, the procedure as in the example of FIG. 6 can be newly started at point 46. However, when attempting to longitudinally crown a workpiece tooth, the tool T is tilted about the axis 10 by an angle during the final reciprocating motion. In FIG. 7, this tilting movement is indicated by a short line representing the tool axis 3 at each turning point. Due to this tilting movement, the tool teeth gradually go deeper into the workpiece towards the end faces 8,9, where much material is cut off,
This results in teeth with crowning.

The direction of rotation can be changed between points 42 and 52, or after point 60 once or several times. However, the change of direction of rotation is not necessary in all cases in two flank contact. On the contrary, very often, satisfactory machining results will be obtained without time-consuming redirection of the direction of rotation.

According to the method described with reference to FIG. 7, conical tooth surfaces and conical spherical tooth surfaces can also be formed on the workpiece. In both cases, the feed infeed must always be greater in one direction of the horizontal feed movement than in the other direction. Furthermore, in order to obtain conical spherical teeth, at the end the tilting movements will correspondingly overlap.

When advancing the process shown in FIG. 8, the tool T is first engaged with the workpiece W, to be precise, in the machining where there is two tooth flank contact between the tool T and the workpiece W. Until the starting point 60 for reaching is reached, it is meshed by reducing the axial spacing, initially fast and then extremely slow and feeding vertically along the radial direction. The work piece has already been displaced somewhat earlier in the direction of rotation when there was still a gap between the teeth of the tool T and the work piece W. The tooth causes the workpiece W to be displaced in the direction of rotation.
Then, when horizontal feeding is performed to the point 61, the contact point N moves from the center position toward the end surface 9 to the turning point P. At the same time as this horizontal feeding, fine feed feeding is performed. That is, this infeed feed is superposed on the horizontal feed-in the subsequent horizontal feed. Next, horizontal feed is performed in the opposite direction from the turning point P to the point 62 where the contact point N reaches the turning point Q. From there, horizontal feed in the opposite direction again occurs at the point 63 where the contact point again reaches the turning point P.
Will be conducted towards. This changing horizontal feed, in which the infeed feed is superposed, is repeated until the target interaxis distance between the workpiece axis 4 and the tool axis 5 at point 66 is reached.
Until this time, the axis intersection always advances only the distance 2 · S ′, and the distance 2 required to process the tooth flank over the entire tooth width.
・ Never go S. This is because the tooth of the workpiece is machined only in the central part, and in the part on the end face side of the following tooth, the end regions 6 and 7 of the tooth surface 5 of the tool are not completely meshed. It means that incomplete cutting is done. The workpiece W has only a slightly concave tooth flank, as can be seen from FIG. 7 where the cutting during several horizontal feeds is shown schematically. This is because the hard edges of the teeth have hardly ever been cut.

After reaching the target inter-axis distance, at least one further horizontal feed is performed. This last horizontal feed, going from point 66 to point 67, then back to point 68, and back again to point 66 (where contact point N is again in the neutral position), does not involve a feed feed. Done. Before pulling the tool T and the work W away from each other again, pull the tool T back slightly from point 66 to point 69,
A new reciprocating motion (points 69, 70, 71, 69) can be interposed. Such a reciprocating motion is used to grind the tooth flank without further cutting a considerable amount of material. Of particular importance is that the points 67, 68 are on the edges of the teeth of the workpiece and therefore the axis crossing always advances a distance of 2 · S, and the tool T is angled during this last reciprocation. Only that it can be tilted around axis 10. In FIG.
This tilting movement is indicated by a short line representing the tool axis 3 at each turning point. This tilting movement causes the tool teeth to dig deeper and deeper into the work piece towards the end faces 8,9, where much material is excised, thereby producing crowned teeth. As shown in FIG. 9, cutting of such material takes place in the wedge-shaped end region indicated by reference numeral 51, and the tool bites into this end region at an acute angle, resulting in a gradual increase. The cutting depth will occur. In this way, the tool is treated with less pain and less pain than with conventional construction methods.

Again, the direction of rotation can be changed between points 60 and 72 once or several times. However, changing the direction of rotation is not necessary in all cases in the case of two flank contact. On the contrary, very often it will be possible to obtain satisfactory machining results without time-consuming redirection of the direction of rotation.

As described above, instead of always defining a horizontal feed of the same length, the feed amount can be increased at least once with a progressive plunge feed, as shown in FIG. Obviously, the central part of the tooth of the workpiece to be machined becomes longer with each expansion of the horizontal feed (No. 10).
Figure).

Also, to improve the tooth flank of the workpiece, the infeed feed (plunge feed), which overlaps with the horizontal feed, can be modified to obtain an initially large feed feed movement and then a progressively smaller feed feed movement. In FIG. 12, each infeed feed amount f ₁ , f ₂ ... Is smaller than each preceding feed amount, in contrast to FIG. 8 in which all infeed feed amounts f have the same magnitude. I'm running.

It is not necessary to overlap the infeed feed with the horizontal feed,
Separate the infeed feed from the horizontal feed,
It is also possible to do this at the turning point as shown in FIG. In this case, the size used in FIG. 8 is the basis. Each turning point has a number, and the corresponding endpoints of the horizontal feed are indexed by A. This non-continuous feed may also be initially large and then small, as described for continuous feed based on FIG. And this horizontal feed is the 10th, 11th
It can be scaled up in the same way as described on the basis of the figures.

In the case of a helical gear, a secondary burr 52 may occur at the tooth end with an acute angle (Fig. 14).
The initial meshing between the workpiece W and the workpiece W is appropriately set so that the starting point 60 overlaps with the above-mentioned point 61 in the region near the obtuse tooth end of the tooth surface. This is indicated by the dotted line in FIG.

The transition from an initial large infeed feed to a small or infeed feed does not have to be made according to a somewhat invariant, machine operator dependent pattern and is measured in the mechanical system via the sensing means. It can also be controlled depending on the applied force, spindle deflection, torque, noise and / or other vibrations. As a sensor,
For example, strain measurement film (DMS,
So-called strain gauges 53, 54 are applicable (15th
Figure). The DMS 53 provided on the drive spindle 12A measures the torque, and the DMS 54 or displacement gauge provided on the tailstock spindle 13A measures the force. The vibration is generated by tailstock spindle 13A and / or tool spindle 3
A directly through the tangential accelerometers 55, 56, or through the microphone 57 or machine part near the tool / workpiece pair, for example, the object acoustic meter 58 in the tailstock 13,
It is possible to perform an indirect detection based on the emitted noise. The value determined by one sensor or possibly several sensors is fed to the machine controller 19, and so is the value determined by the rotary transmitter 59 of the drive motor 1. There, the various motors 1 which are supplied there, are compared with corresponding predetermined values there and
Converted to the signal as it is carried on 7, 22, 30, 32, 34.

[Brief description of drawings]

Several embodiments are shown in the drawings. 1 and 2 are front and side views of a machine capable of carrying out the method of the present invention, FIG. 3 is a side view of the tool of FIG. 1 meshing with a workpiece, and FIG. 4 is a workpiece. 5 is a plan view of the tool with FIG. 5, FIG. 5 is an enlarged view of the state of FIG. 4, particularly a simplified view of various positions of the tool, and FIGS. 6, 7 and 8 are views of steps of the method of the present invention. One schematic example, FIG. 9 shows multiple cutting steps of the tooth of the workpiece in the process of FIG. 8, FIG. 10 shows another schematic example of the process which is the method of the present invention, FIG. The figure shows a number of cutting steps of the tooth of the workpiece in the process of FIG. 10, FIGS. 12 and 13 show two other schematic examples of the process which is the method of the invention, and FIG. A cross-section of one tooth of a cut workpiece, FIG. 15, shows the arrangement of the sensing means in the machine of FIG. 1 ... Drive motor, 3 ... Tool T axis, 3A ... Tool spindle, 4 ... Workpiece W axis, 5 ... Tool T tooth surface, 6, 7 ... Tooth surface end region, 8,9 …… End face of the workpiece W,
10 …… Axis, 11 …… Machine bed, 12,13 …… Tailstock, 1
2A …… Drive spindle, 13A …… Tailstock spindle, 1
4 …… Transmission belt, 15 …… Column, 16 …… Vertical feed carriage, 17 …… Motor, 18 …… Spindle, 19 …… Machine control device, 20 …… Horizontal feed carriage, 21 …… Axis, 22
...... Motor, 23 ...... Spindle, 24 ...... Arc guide, 25
...... Rotker, 27 …… Tool head, 28 …… Axis line, 29 ……
Central rotating surface, 30 …… motor, 31 …… rod, 32 …… motor, 33 …… worm gear device, 34 …… motor, 35 …… transmission device, 40 to 49 …… point of tool T during horizontal feed , 51 ... Edge area, 52 ... Secondary burr, 53, 54 ... Strain measurement film, 55, 56 ... Accelerometer, 57 ... Microphone, 58 ...
… Object sound meter, 59 …… Rotating transmitter, 60〜63,66
~ 71 …… Point of tool A during horizontal feed, 72 …… Displacement meter, N ・ ・ ・
… Contact point, P, Q… Turning point, T… Tool, W… Workpiece, X… Horizontal feed, Z… Infeed (plunge)
Feed, f ₁ , f ₁ , f ₂ …… Infeed feed amount, S, S ′ …… X
Distance, gamma ...... axis crossing angle, epsilon ...... diagonal angle, ... tilt angle, b _T ... width of the tool T, b _W ... workpiece W in width, u ... Obaratsupu

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 62-228320 (JP, A) JP 58-82622 (JP, A) JP 53-16994 (JP, A)

Claims (9)

[Claims] 1. A crowned tooth surface of a hardened gear (workpiece) is brought into contact with a gear-shaped or rack-shaped tool in a two-sided manner, and the tool and the workpiece are attached along respective axes. A method of performing precision machining by intersecting at a certain intersecting angle, wherein the tooth flank of the tool is provided with a hard abrasive layer, a polishing surface, that is, a surface having no unidirectional cutting edge. The tool has at least one reciprocating horizontal feed to the workpiece and at least one reduction of the axial distance;
A continuous or discontinuous infeed feed (plunge feed) is carried out, the horizontal feed being perpendicular to the common normal of the tool and the workpiece and to the axis of the workpiece. In a certain angle (ε), and after reaching the target inter-axis distance at least one more horizontal feed (X) without plunge feed, Tool (T) has at least one horizontal feed (X) without plunge feed
During the first time, the tilting movement (K) is carried out about the axis (10), which at least approximately abuts the pitch cylinder of the tool (T) and which is connected to the common axis (N). A method for precision machining a crowned tooth flank of a hardened gear, characterized in that it is at right angles to it and also to the axis (4) of the workpiece. 2. A) The horizontal feed movement performed in relation to the plunge feed is the distance traveled in the axial direction by the axial intersection on the workpiece (W), and the axial intersection is at the edge of the tooth surface. It is set to finish before reaching. B) The horizontal feed performed without the plunge feed is such that the distance the axial intersection advances in the axial direction on the workpiece (W) at the earliest. The method according to claim 1, wherein the axis intersection is set to end when the edge of the tooth surface is reached. 3. All horizontal feeds made with the plunge feed are of the same length.
The method described. 4. A) horizontal feed performed in connection with the plunge feed, wherein the axial crossing on the workpiece (W) is at least at the start of the axial crossing, and the axial crossing is the tooth crossing. End before reaching the edge of the surface,
The method according to claim 2, wherein it is set to expand at least once as the plunge feeding progresses. 5. The method according to claim 1, wherein the horizontal feed carried out together with the plunge feed is continuously expanded. 6. The method according to claim 1, wherein the horizontal feeding is started at a position other than the center with respect to the tooth flank. 7. The plunge feed is initially carried out at a first feed rate or step width and then after a selectable inter-axis distance is reached, a second feed rate decelerated with respect to the first feed rate. 7. The method according to claim 1, wherein the feeding speed or the step width is used. 8. The plunge feed is first performed at a first feed rate or step width and then based on force and deflection and torque and / or noise and / or other vibrations measured by the sensing means. The first
8. A method as claimed in any one of the preceding claims, characterized in that it is decelerated to at least a second feed rate or step width which is decelerated with respect to the feed rate. 9. The following relational expression between the inclination angle (ε) and the axis intersection angle (γ): 9. The method according to any one of claims 1 to 8, characterized in that